JP2008547063A - UV curing apparatus having a combined optical path - Google Patents

Abstract

  The present invention provides a curing in which the light source (11, 16) includes at least two light sources (11, 16) combined in one optical path, capable of curing the material (15) exposed in one combined optical path. Concerning the assembly. The present invention also provides a material associated with the curable material or heat sensitive material; and exposing the pre-curable material to the coalescing optical path from the cured assembly, the curable material (15) or the heat sensitive material. The present invention relates to a method for curing a material in contact with a material.

Description

  The present invention relates to a roll-to-role treatment of ultraviolet (UV) curable materials in flexible displays. Specifically, the present invention can be used in the production of polymer dispersed chiral nematic liquid crystal displays on flexible or heat sensitive substrates. The present invention also relates to an apparatus for curing UV-initiated materials, particularly polymers, used in roll-to-roll manufacturing of flexible displays. Specifically, the present invention can be used to cure ultraviolet (UV) photosensitive inks used in the fabrication of liquid crystal displays on flexible or heat sensitive substrates.

  Currently, information is displayed using a laminated paper sheet carrying permanent ink or displayed on an electronically modulated surface such as a cathode ray display or a liquid crystal display. The printed information displayed in this way cannot be changed. Devices that allow changes in information, such as electrically updated displays, are often heavy and expensive. For example, information can be added to the sheet material via the magnetic writing area to carry ticket information or financial information. However, such data written magnetically is not visible.

  There are media systems that maintain electronically variable data without power. Such a system can be an electrophoretic material (Eink), a Gyricon, or a polymer dispersed cholesteric material. An example of such an electronically updatable display is a U.S. Pat. No. 5,849,900 showing a cholesteric liquid crystal emulsion in coated and then dried aqueous gelatin to form a field responsive bistable display. It can be found in the specification of 3,600,060. U.S. Pat. No. 3,816,786 discloses an encapsulated cholesteric liquid crystal layer that is responsive to an electric field. The electrodes described in this specification may be transparent or opaque and can be formed from various metals or graphite. It is disclosed that one electrode must be light absorbing and it is suggested that the light absorbing electrode is prepared from a conductive material, such as a paint containing carbon.

  The fabrication of an electronically writable flexible display sheet is disclosed in US Pat. No. 4,435,047. The substrate carries a first conductive electrode, one or more encapsulated liquid crystal layers, and a second electrode of conductive ink. Since the conductive ink forms a background for absorbing light, the information carrying display area appears dark as opposed to the non-display area of the background. The potential applied to the opposing conductive area acts on the liquid crystal material to expose the display area. Since the liquid crystal material is a nematic liquid crystal, the display stops providing an image when the energy is turned off, i.e. when the field is absent. A first flexible substrate is patterned and applied. A second pre-patterned substrate is bonded onto the coating film.

  US Pat. No. 5,251,048 discloses a light modulation cell having a polymer-dispersed chiral nematic liquid crystal. Chiral nematic liquid crystals have the property of being electronically driven between a planar state that reflects a specific visible wavelength of light and a focal conic state that transmits scattered light forward. Chiral nematic liquid crystals, also known as cholesteric liquid crystals, potentially have the ability to maintain one of a number of given states in the absence of an electric field in some environments. Applying black paint to the outer surface of the back substrate to provide a light absorbing layer that forms a non-changing background outside the variable display area defined by the intersection of the segment lines and scan lines Can do. A first glass substrate is patterned. The patterned second glass substrate can be fixed with a space from the first substrate. The cavity is filled with liquid crystal.

  U.S. Pat. No. 6,394,870 discloses depositing opaque conductive ink directly in an imagewise pattern by screen printing. The conductor is printed directly on the polymer dispersed cholesteric material. A display having such a configuration requires a light-absorbing back layer. The invention forms a light absorber by printing a second conductor formed by screen printable carbon in a resin matrix. Carbon absorbs visible radiation, but also absorbs UV light that can be used to cure UV-responsive conductive formulations. If UV curable silver ink is used, the contrast formed between the planar state and the transmissive focal conic state by silver reflection is negligible. The process of drying an opaque conductive ink requires many minutes to cure the ink.

  Allied Photo Chemical's photocurable silver composition is disclosed in US Pat. No. 6,290,881. The composition consists of an ultraviolet curable organic mixture, a photoinitiator, silver powder, and a silver flake composition. The silver flake composition comprises at least 20% by weight of the silver powder. The disclosed compositions can be used to produce silver-containing coatings on different substrates. However, this material is not disclosed for use in display devices, and this specification does not disclose a method for photocuring ink in a display device or on a heat sensitive substrate. Not in. This should be useful for flexible or heat sensitive displays that are to be fabricated using a simple low cost process. Such a process could also include an inexpensive high-speed method for forming the second conductor, such as in a roll-to-roll processing apparatus.

US patent application Ser. No. 10 / 847,188 discloses a dye that has been applied to a polymer dispersed cholesteric liquid crystal and dried to form a complementary light absorbing layer. A second conductor was printed on the complementary light-absorbing layer using a photosensitive silver filled polymer thick film ink, for example, UVAG® 0010 resinous material from Allied Photochemical, Kimball, Michigan. After printing a polymer thick film (PTF) ink on a panel of polymer dispersed cholesteric liquid crystal and a dye on a flexible support, 0.20 Joules / cm ² to form a durable and conductive surface The ink was exposed to higher UV radiation. Without a mechanism to eliminate or remove the infrared (IR) component of the spectrum of emitted light absorbed by the target UV curable material, the thermosensitive liquid crystal will undergo a thermal transition at these curing energies. Approximately 24 hours after exposure to the UV light source, the exposed ink reached its specified conductivity. However, until the specified conductivity is reached, some of the ink material will migrate to the back side of the stacked or wound panel on the cured ink surface. To facilitate the roll-to-roll manufacturing process, avoid any thermal transition of the liquid crystal and any tendency to transfer UV-cured ink to the back of the next roll while being wound on the roll. It would be desirable to be able to cure the ink in a manner that would eliminate it. Furthermore, it is desirable to cure the UV ink more completely to increase conductivity, hardness, and adhesion to the substrate.

  A curing unit and ink curing method is disclosed in US Pat. No. 5,216,820. This invention relates generally to curing devices for use in screen printing, and more specifically to an apparatus for curing photoinitiated polymer-based inks applied to flat and three-dimensional articles. SUMMARY OF THE INVENTION The present invention relates to a cover assembly with a dual chamber in which a reflector assembly containing a curing lamp and means for exhausting air from the chamber of the cover are arranged. The invention further utilizes a cover assembly comprising an inner cover and an outer cover forming an outer cooling chamber therebetween, and an inner cooling chamber between the inner cooling chamber and the reflector assembly. Enables process heat reduction. The invention also includes a reflector assembly having at least one opening in its outer surface and disposed within a cover that defines an outer chamber. The unit further includes means for exhausting heated air from the curing chamber, means for drawing air into the outer chamber through at least one opening provided in the cover, and exhausting air from the outer chamber. Including. The ends of the cover assembly form ducts that communicate with the means for exhausting air from the cover chamber. The exhaust means draws external cooling air into the outer cooling chamber through an opening in the outer cover and exhausts the air to cool the unit. However, this patent does not disclose use for display devices, such as flexible displays containing heat sensitive materials. Furthermore, there is no mechanism for eliminating or removing the IR component of the spectrum of emitted light absorbed by the target UV curable material. This IR component must be minimized to avoid thermal transitions of the heat sensitive substrate, eg, cholesteric liquid crystals.

  A paper entitled “The process window of UV-cured inkjet printing” from SGIA Journal in the second quarter of 2004 was published in the depth and surface of UV-sensitive inks or coatings. It suggests the significance of different UV wavelengths for polymerization. The paper shows that the most basic mercury bulb containing additives emits energy at both long and short wavelengths, which is absent from particles or relatively thin in the deposited material to be cured. In some cases, this suggests that it is sufficient to allow both deep and surface curing. Curing depth (long wave) is important for proper adhesion of the ink to the substrate, and surface curing (short wave) is important because no blocking of the stacked or wound substrate occurs. . Testing with a single-valve UV curing form to cure UV-sensitive silver-containing inks such as Allied Photochemical's UVAG 0010® is sufficient to allow a roll-to-roll manufacturing process. It indicates that no curing occurs. To cure the ink in a roll-to-roll process, achieve sufficient cure so that the ink on the substrate can be wound on a roll shortly after UV exposure without concern for adhesion failure or blocking Is advantageous.

  Irradiation of UV curable ink on an opaque surface, for example a PDLC coating containing a light absorbing layer between PDLC and light curable ink, the ink can be rolled up in a roll-to-roll manufacturing process Does not cure sufficiently until it causes some ink transfer to the backside of the subsequently wound layer. The physical properties of UV curable materials are affected by the radiation source used to cure these materials. Physical properties such as the thickness of the curable material, as well as the presence of silver particles and flakes, diffusivity and absorption capacity require a balance of the wavelength parameters of the radiation source. As discussed in “The process window of UV-cured inkjet printing”, RW Stowe, SGIA Journal, 2nd quarter 2004, pages 3-6. Moreover, it is known that short wavelengths act on the surface, whereas long wavelengths penetrate deeper into the material. Insufficient exposure of the curable material results in inadequate curing, low resistivity in the case of conductive materials, and blocking, i.e., roll-to-roll curable material transition when the roll is wound after processing. Cause it to occur.

  A commercially available UV curing device consisting of a model LC-6B conveyor assembly and two F300S UV lamp assemblies is shown in FIG. 5, which is a silver-containing photoinitiator in the paneling process. Allows rapid curing of the ink, but this is not done in a roll-to-roll process. One application of this tool allows the user to expose the substrate to two different UV spectra generated from two different types (doped) UV lamps. The advantage of using different spectra allows for deep and surface activation of the photoinitiator in the ink by utilizing long and short UV wavelengths. This process is well known to those skilled in the photocuring art. One drawback of this type of system is that it also creates high levels of heat in the form of IR waves and hot air resulting from lamp cooling, which can be detrimental to heat sensitive substrates. There is. Exposure of the PDLC surface to the IR spectrum can lead to thermal transition of the PDLC layer and can also cause thermal damage to the flexible substrate. In addition, the Fusion lamps are spaced apart from each other and illuminate different areas of the curable material, which results in non-uniform curing of the material. For small articles, the system cannot expose a small area to both light sources in a single pass, increasing the manufacturing complexity. In the case of exposure with two different UV lamp spectra, a back and forth movement is required to cure the intimate panels. In particular, the roll-to-roll operation pauses the substrate so that the printed area is applied to both lamps while the substrate under the gap between the two light sources is applied to only one light source. If so, it would be useful to combine two different UV lamp spectra into one light path to better facilitate roll-to-roll processing of the display. This condition results in noticeable and possibly unacceptable cure variations. The most prominent factor is that even a small time delay on the order of less than a second between exposures results in a less rapid and less complete cure than when exposed simultaneously to different spectra of two different lamps.

  An illumination system for combining light from two separate light sources is disclosed in US Pat. No. 6,341,876. The present invention relates to an illumination system for generating a light beam for illuminating a spatial light modulator that generates a spatially modulated light beam that can be projected onto a display screen. However, this invention does not disclose use in a UV curing chamber to cure photosensitive ink, and how to minimize the IR spectrum to avoid thermal transfer of the heat sensitive substrate. It is not disclosed whether it can be suppressed.

  U.S. Pat. No. 6,621,087 discloses a device having at least one light source disposed above a substrate for curing a UV coating on the substrate, specifically a heat sensitive material. The light is directed to the UV coating through a reflector system that includes at least one barrier that prevents the direct beam path of the light source from impinging on the substrate. The UV radiation emitted by the light source is reflected by the barrier's UV reflective coating, through the light source, to a reflector located behind the light source, and the barrier absorbs at least one heat radiation emitted by the light source. Includes heat absorber. In one embodiment of the invention, it is possible to focus UV rays on the substrate. In order to reduce the thermal load on the substrate and at the same time achieve high UV intensity through the short beam path required for curing, the present invention makes it possible to effectively separate UV radiation from IR radiation. However, U.S. Pat.No. 6,621,087 does not combine multiple light sources into a single pass to achieve improved cure and facilitate roll-to-roll or discontinuous part manufacturing. Not involved.

  There is now a system that produces more rapid, uniform, and complete curing of UV curable materials that can be used in roll-to-roll or continuous type manufacturing operations, especially when the curable material is in contact with a heat sensitive material. It is necessary.

  The present invention is a cured assembly comprising at least two light sources, each of the at least two light sources having a spectrum, each spectrum of at least two light sources being combined in one optical path, and at least 2 It relates to a cured assembly in which one light source can cure material exposed to one coalescing light path. A method or process for curing a material comprising providing a curable material and exposing the curable material to a coalescing light path from the cured assembly, the cured assembly including at least two light sources. Each of the at least two light sources has a spectrum, each spectrum of the at least two light sources is merged into one optical path, and at least two light sources cure the material exposed to one merged optical path A material curing method or process is provided that can be provided.

  The present invention includes several advantages, not all of which are incorporated into a single embodiment. The present invention allows for rapid, uniform, and complete curing of UV or radiation curable materials through the use of multiple light source spectra, and these spectra are combined into a single optical path so that UV curing is possible. The photosensitive substrate is exposed simultaneously to the radiation spectra from both light sources. Simultaneous exposure of the short wavelength spectrum exposure that is more effective to stimulate the UV polymerization initiator on the surface and the longer wavelength radiation spectrum exposure that is more effective to stimulate the UV polymerization initiator deep in the UV curable material When done, it provides a faster and more complete polymerization across the UV curable material than occurs from separate exposures to multiple light sources, even with a small time offset.

  The present invention is useful as an enhancement means for these roll-to-roll operations, unlike prior art processes that require forward / backward movement of oriented / adjacent panels on the web. By incorporating a long UV spectrum and a short UV spectrum, dual wavelength UV exposure of silver-containing inks allows for rapid fabrication and curing of UV curable deposited conductors. The present invention eliminates blocking, i.e., transfer of uncured material to the contacting surface when in the form of a wound roll, by allowing for quicker and more complete curing of the material prior to winding. Or significantly reduced and also provides a more conductive cured material.

  The present invention also enables thermal management, which is an important issue in the case of heat sensitive materials that may support or contact the curable material, or may be the curable material itself.

  The present invention relates to curing a radiation curable material by exposing the material to a cured assembly having at least two light sources combined to form a combined optical path. The invention also relates to an improved method of rapid and complete curing for UV curable coatings, adhesives, sealants, printed materials, sprayed materials, and materials applied by any means. The present invention relates to a material applied to a continuous web, panel, or any structure applied with a UV curable material that can be exposed to a single beam consisting of two or more distinct light sources. Can be used to cure. The present invention employs current technology for rapid and complete curing of the thickness of the material to be cured, the presence of particles, the flakes or droplets in the UV curable material, or the heat sensitivity of the UV curable material or substrate. This is especially useful when it is difficult to achieve.

  Such a need exists with roll-to-roll processing of UV curable materials in flexible displays. Rapid cure in a roll-to-roll process will allow for winding without transfer of material to the backside of a subsequent roll. A more complete cure provides improved conductivity of the conductive ink, with improved hardness and adhesion to the substrate. Specifically, the present invention can be used when manufacturing a polymer-dispersed chiral nematic liquid crystal display on a flexible substrate or a heat-sensitive substrate. The invention also relates to an apparatus for curing UV-initiated polymers used in roll-to-roll manufacturing of flexible displays. Specifically, the present invention can be used to cure ultraviolet (UV) photosensitive inks used in the manufacture of liquid crystal displays on flexible or heat sensitive substrates.

  The present invention provides an apparatus and process for use in a continuous or intermittent operation mode or a static exposure mode. The present invention is particularly useful in intermittent roll-to-roll operations where the substrate is paused during operation, eg, printing. In such an intermittent roll-to-roll operation, if the light source is offset in distance, some substrate will be exposed for a significant time by only one spectrum. This delay causes variations in the curing effect within the roll length, which is undesirable.

  Minimizing the IR spectrum in the radiation that exposes the substrate by adding an infrared reflective or absorbing filter, and a filter that has the same wavelength as any light absorbing layer in the UV optical path, during the UV curing process, If present, the heat sensitive layer and the temperature induced in the substrate are greatly reduced. Further heat reduction is achieved by isolating the light source chamber from the transport mechanism where the substrate is held.

Any light source can be used as long as the spectrum of the light source is compatible with the spectral sensitivity of the photoinitiator in the curable material. A spectrum is defined as a predetermined wavelength range. As used herein, wavelength refers to a specific numerical value determined by the distance between adjacent peaks, also called crests in the wave train. The number of such crests that pass through a fixed point in one second is known as the frequency (1 crest per second = 1 hertz), and short wavelengths thus imply high frequencies. For light, the unit of wavelength is angstroms (Å) measured as 10 ^-10 meters. Visible light is 4,000-7,500mm. Wavelengths in this range are perceived by the naked eye as different spectral colors. Preferably, the light source is a UV source, which in the case of the present invention inherently contains some IR. The light source can include a spectral range in the visible light range, invisible light range, and combinations thereof. In one embodiment, the light sources preferably have different spectral ranges. However, multiple light sources may have the same or overlapping spectral ranges. The light source may include mostly short wavelength bulbs, such as Fusion UV, Inc. H bulbs, and mostly long wavelength bulbs, such as Fusion UV, Inc. D bulbs. In one preferred embodiment, the cured assembly utilizes at least one short wavelength UV bulb in combination with at least one long wavelength UV bulb.

  An optical path means a beam or column of light. The merged optical path can be determined by measuring the spectral output of the merged beam and detecting the presence of the spectrum from both light sources.

  The light sources can be combined to form a single optical path in a variety of ways. In one embodiment, multiple light sources are arranged so that the beam generated by each light source irradiates the same area on the material to be cured. In one embodiment, the light source can be directed to the coalescing mirror, and the mirror merges multiple optical paths into one. In another aspect, the light source can be directed to a refractive element, such as a lens, which combines or converges multiple optical paths into a single combined optical path. A combination of refractive elements and mirrors can also be used. In another embodiment, a reflective surface is used to funnel the light to the UV curable material to increase the exposure. In other embodiments, a shutter, rotary valve, aperture, or slide gate can be used to expose the target or block UV light to the target. By combining the light source into a single path, the ability to expose or not expose the target UV curable material is simplified for those skilled in the art.

  At least one reflector can be used to change the direction of the radiation source's spectrum. Preferred reflectors are mirrors, lenses, and combinations thereof. In an exemplary embodiment, at least one mirror is associated with each light source. “Related” means that the mirrors are at least close enough to affect the light source. The mirror may be any mirror that can change the direction of the optical path. The mirror can have a spherical or parabolic surface to improve the efficiency of the amount of transmitted light. The mirror may be a coalescing mirror that redirects the light source to a single path. There may be a folding mirror or funneled mirror that redirects the light source output to the coalescing mirror. The mirror can also have means for independently adjusting the light incident angle from the folding mirror to the substrate.

  The mirror can be processed in a wide variety of ways. In one embodiment, the mirror is treated with a dichroic surface coating. The dichroic coating may be able to absorb or reflect portions of the light source spectrum, but preferably transmits most of the UV spectrum. In the preferred embodiment, the reflector is a dichroic elliptical reflector. In one preferred embodiment, the dichroic coating absorbs or reflects in the IR spectral region. These dichroic coating film-containing reflectors can be called hot mirrors or cold mirrors. Hot mirrors absorb part of the spectrum. A cold mirror reflects a portion of the spectrum.

  The refracting element is intended to change the direction of the output from the light source here to improve or maximize the amount of light that converges into one optical path and reaches the cured surface. Refractive elements can be used to focus light, combine light, or a combination thereof. Although any element that can collimate light can be used, the preferred refractive element is a lens. In one embodiment, the lens is a fused silica lens.

  One or more filters can be used alone or in combination with reflectors, refractive elements, or combinations thereof. The combined light can pass through an optical filter, an infrared filter, a quartz plate, or any possible combination of filters to reach the substrate. In a preferred embodiment, the filter is a visible light filter. The filter selectively reduces the portion of the spectrum that reaches the cured surface. The filter can also help reduce the heat generated by the light source by isolating the light source from the curable material while allowing the combined optical path to be transmitted to the curable material on the substrate. In the case of heat sensitive materials, the filter can be adapted to the absorption capacity of the heat sensitive material to selectively remove the wavelength or wavelength range that the heat sensitive material is sensitive to. For example, the filter may be a blue filter.

  The spectral output intensity can be adjusted. In the case of a refractive element, the intensity can be modified by adjusting the focal length. The focal length is the distance from the curable material to the light source. For example, the support may be out of focus by a total of 3 inches. Another intensity adjustment method may be by changing the angle of incidence. Yet another intensity adjustment method may be to adjust the lamp output intensity. A shutter or aperture can also be used to control the spectral output.

  A heat reduction system is preferably included in the cured assembly. The heat reduction system can remove heat radiation (heat) from the assembly to reduce the effects of radiation curing on any heat sensitive material. By using infrared mirrors or absorbers, filters, eg visible spectral filters in the optical path, air flow or air exhaust systems, heat sinks, heat exchangers, or by isolating the lamp chamber from the substrate, or these Any combination of can achieve a reduction in heat. Isolation can be achieved by using a shutter, aperture, or light filter, typically placed between the light source and the curable material. In one preferred embodiment, the curing assembly chamber configuration limits the amount of heat from the lamp to the support by redirecting the lamp supply cooling air to the upper chamber exhaust port. The upper / lower chamber isolation assembly can help isolate the upper and lower chambers and also reduce the amount of heat sensed by the substrate on the transport belt. In one embodiment, cooling air is drawn into the assembly through the infrared mirror / absorber and a visible spectral filter in the optical path, and the heated air is removed, and the lamp is further substrated By isolating it from the heat reduction is achieved. The substrate can be further cooled by a cooling mechanism in the transport belt.

  The curable material may include any UV curable material, by application, printing, spraying, jetting, flooding, transferring from a donor, or any method that results in a UV curable material deposited on the surface. Can be applied. The curable material may include materials that require some chemical mechanism for curing, such as crosslinking and evaporation of the carrier solvent. In one embodiment, the curable material may include a polymeric material. The curable material can be in the form of, for example, an imageable layer, a light modulating layer, a printable conductive ink, a conductive layer, a color contrast layer, a dielectric layer, a sealant, an adhesive, a paint, a protective coating, and a barrier layer. It may be made. The curable material can be applied directly to the substrate, or it can be applied with a carrier material, such as a solvent, that can be removed later to facilitate the curing process.

  The curable layer may include a dielectric material. For the purposes of the present invention, a dielectric layer is a layer that is not conductive or blocks the flow of electricity. The dielectric material may comprise a UV curable, thermoplastic screen printable material such as Electrodag 25208 dielectric coating from Acheson Corporation. The dielectric material forms a dielectric layer. This layer may include an opening for defining an image area, the image area coinciding with the opening. Since the image is viewed through the transparent substrate, the display object is imaged as a mirror image. The dielectric material can subsequently form an adhesive layer for bonding the second electrode to the light modulating layer.

  When utilizing an ink containing a photosensitive oligomer, the curing process occurs by any means known to those skilled in the art of coating curing, for example by applying light, heat, or some other energy source. be able to. Photoactivation of the curing process can occur by exposure to ultraviolet light, visible radiation, infrared light, or a combination thereof, and the curing process can then be chemically reacted, for example by cross-linking polymerization, to cure the material. Start.

A typical curing process for a roll-to-roll operation takes place in several steps: (a) initiation, (b) machine transport curing, and (c) take-up roll curing. There are two main methods of curing the coating: actinic and thermal. In the case of actinic radiation curing, the polymerization of prepolymer inks having a volatile content of less than 10% is initiated by application of electromagnetic energy. UV wavelengths below 386 nanometers are used for this process. The dose limit is 100 to 700 mJ / cm ² , preferably 200 to 500 mJ / cm ² . Temperature and airflow are standard for those skilled in the art. When using the prior art, curing was not fast enough or complete after UV exposure to allow winding without additional time to fully complete the curing process. In a wound roll, the web requires time without contact between the windings to fully cure so that the material is not transferred (blocked) to the back side of the subsequent roll.

  In the case of the present invention, a curable material is typically applied to a support referred to herein as a substrate. The curable material can be applied to the support by any method known to those skilled in the art to form a layer. Some example methods can include screen printing, hopper coating, gravure printing, lithography and photolithography printing, ink jet printing, spraying, and vapor deposition.

  Preferred supports are plastic supports, most preferably flexible. The flexible plastic substrate may be any flexible self-supporting plastic film that supports a thin conductive metal film. “Plastic” means a polymeric compound, usually formed from a polymeric synthetic resin, that can be combined with other components such as curing agents, fillers, reinforcing agents, colorants, and plasticizers. Plastic includes thermoplastic materials and thermosetting materials. A preferred support is a plastic support, but other types of supports can be used including, by way of example, glass, metal, wood, and fabric.

  Typically, flexible plastic substrates are polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), polysulfone, phenolic resin, epoxy resin, polyester, polyimide, poly Ether ester, polyether amide, cellulose acetate, aliphatic polyurethane, polyacrylonitrile, polytetrafluoroethylene, polyvinylidene fluoride, poly (methyl (x-methacrylate), aliphatic or cyclic polyolefin, polyarylate (PAR), polyether Imide (PEI), polyethersulfone (PES), polyimide (PI), Teflon (registered trademark) poly (perfluoro-alkoxy) fluoropolymer (PFA), poly (ether ether ketone) (PEEK), poly (ether ketone) ( PEK), poly (ethylene tetrafluor) (Polyethylene) fluoropolymer (PETFE) and poly (methyl methacrylate) and various acrylate / methacrylate copolymers (PMMA) Aliphatic polyolefins are high density polyethylene (HDPE), low density polyethylene (LDPE), and stretched Polypropylene, including polypropylene (OPP) can be included, and the cyclic polyolefin can include poly (bis-cyclopentadiene)). Preferred flexible plastic substrates are cyclic polyolefins or polyesters. Various cyclic polyolefins are suitable for flexible plastic substrates. Examples are Arton® from Japan Synthetic Rubber Co. (Tokyo, Japan); Zeanor T from Zeon Chemicals LP (Tokyo, Japan); and Topas® from Celanese AG (Kronberg, Germany). including. Arton is a poly (bis-cyclopentadiene)) condensate that is a film of polymer. Alternatively, the flexible plastic substrate may be polyester. Preferred polyesters are aromatic polyesters such as Arylite. While various examples of plastic substrates are shown above, it will be appreciated that the substrates can be formed from other materials such as glass and quartz.

  The flexible plastic substrate can be reinforced with a hard coating. Preferably, the hard coating film is an acrylic coating film. Such hard coatings are typically 1-15 microns thick, preferably 2-4 microns, and can be provided by radical polymerization. Radical polymerization is initiated by heat or ultraviolet light with a suitable polymerizable material. Depending on the substrate, different hard coatings can be used. If the substrate is polyester or Arton, a particularly preferred hard coating is the coating known as “Lintec”. Lintec contains UV curable polyester acrylate and colloidal silica. When deposited on Arton, the hard coating has a surface composition consisting of 35 atomic% C, 45 atomic% O, and 20 atomic% Si, excluding hydrogen. Another particularly preferred hard coating is an acrylic coating sold under the trade name “Terrapin” by Tekra Corporation in Wisconsin, New Berlin.

  In a preferred embodiment, the curable material is associated with, in particular in contact with, at least one heat sensitive material. “Related” means that when the curable material is cured, the curable layer is at least close enough to affect the temperature of the thermosensitive layer. For example, the curable material can be coated on a heat sensitive support or a bistable liquid crystal layer. The thermosensitive material may be a curable layer or may be a component of the curable layer. There may be an intervening layer, such as a pigment layer, between the curable material and the heat sensitive material. However, the intervening layer cannot reduce the thermal transition between the curable material and the heat sensitive material to a level below that which can affect the heat sensitive material.

  The heat sensitive material may preferably be an imageable material. The imageable layer may be an electrically imageable material. The electrically imageable material may be a luminescent material or a light modulating material. The luminescent material may be inorganic or organic in nature. Particularly preferred are organic light emitting diodes (OLEDs) or polymer light emitting diodes (PLEDs). The light modulating material may be reflective or transmissive. The light modulating material may be an electrochemical material, an electrophoretic material, such as Gyricon particles, an electrochromic material, or a liquid crystal. The liquid crystal material may be twisted nematic (TN), super twisted nematic (STN), ferroelectric, magnetic, or chiral nematic liquid crystal. Particularly preferred are chiral nematic liquid crystals. The chiral nematic liquid crystal may be a polymer dispersed liquid crystal (PDLC). However, to provide additional advantages in some cases, a structure having a stacked imaging layer or multiple support layers is arbitrarily selected.

  Suitable materials may include electrically modulated materials disposed on a suitable support structure, for example on or between one or more electrodes. As used herein, the term “electrically modulated material” is intended to include any suitable non-volatile material. Suitable materials for the electrically modulated material are described in US patent application Ser. No. 09 / 393,553 and US Provisional Patent Application No. 60 / 099,888.

  In a preferred embodiment, the electrically imageable material is addressed with an electric field and then maintains the image after the electric field is removed. This property is typically referred to as “bistable”. Particularly suitable electrically imageable materials exhibiting “bistable” are electrochemical materials, electrophoretic materials such as Gyricon particles, electrochromic materials, magnetic materials, or chiral nematic liquid crystals. Particularly preferred are chiral nematic liquid crystals used in liquid crystal displays.

  The electromodulating material may be a printable ink having an array of particles or microscopic containers or microcapsules. Each microcapsule contains an electrophoretic composition of a fluid, such as a dielectric fluid or an emulsion fluid, and a suspension of colored or charged particles or colloidal material. The diameter of the microcapsules is typically 30-300 microns. According to one aspect, the particles visually contrast with the dielectric fluid. According to another example, the electrically modulated material can be rotated to show different colored surface areas and can be rotated between a front viewing position and a rear non-viewing position, For example, gyricon may be included. Specifically, gyricon is a material comprised of a torsional rotating element contained in a liquid-filled spherical cavity and embedded in an elastomeric medium. The rotating element can be formed to exhibit a change in optical properties by being subjected to an external electric field. When an electric field of a given polarity is applied, a segment of the rotating element rotates towards the viewer of the display and this can be viewed by the viewer. When a field of opposite polarity is applied, the element is rotated and a second different segment is revealed to the observer. A gyricon display maintains a given configuration until an electric field is actively applied to the display assembly. Gyricon particles typically have a diameter of 100 microns. Gyricon materials are disclosed in US Pat. Nos. 6,147,791, 4,126,854, and 6,055,091.

  According to one embodiment, the microcapsules can be filled with charged white particles in a black or colored dye. Examples of electrically modulated materials and methods of making assemblies that can control or achieve ink orientation suitable for use with the present invention are described in WO 98/41899, WO 98/41899. It is shown in the 19208 pamphlet, the 98/03896 pamphlet, and the 98/41898 pamphlet.

  The electrically modulated material can also include the materials disclosed in US Pat. No. 6,025,896. This material comprises charged particles in a liquid dispersion medium encapsulated within a number of microcapsules. The charged particles may have different types of color and charge polarity. For example, white positively charged particles can be employed together with black negatively charged particles. Since the microcapsule is disposed between a pair of electrodes, a desired image is formed and displayed by the material by changing the dispersion state of the charged particles. The dispersion state of the charged particles can be changed through a controlled electric field applied to the electrically modulated material. According to a preferred embodiment, the particle diameter of the microcapsules is from 5 microns to 200 microns, and the particle diameter of the charged particles is a size that is 1/1000 to 1/5 of the particle diameter of the microcapsules.

  Furthermore, the electrically modulated material may include a thermochromic material. Thermochromic materials can change their state alternately between transparent and opaque when heat is applied. Thus, the thermochromic image forming material develops an image by applying heat to specific pixel positions in order to form an image. Thermochromic imaging materials maintain a particular image until heat is reapplied to the material. Since the rewritable material is transparent, the underlying UV fluorescent printing, design and pattern can be seen through the rewritable material.

  The electrically modulated material can also include a surface stabilized ferroelectric liquid crystal (SSFLC). Surface-stabilized ferroelectric liquid crystal confines a ferroelectric liquid crystal material between closely spaced glass plates in order to suppress the natural helical form of the liquid crystal. The cell switches quickly between two optically distinguishable stable states by simply changing the sign of the applied electric field.

  Magnetic particles suspended in an emulsion contain additional imaging materials suitable for use with the present invention. In order to create, update, or change a display that can be read by humans and / or machines, a pixel formed of magnetic particles is changed by applying a magnetic force. It will be apparent to those skilled in the art that various bistable non-volatile imaging materials are available and can be implemented in the present invention.

  The electrically modulated material can also be configured as a single color, such as black, white or transparent, and can be fluorescent, iridescent, bioluminescent, incandescent, ultraviolet, infrared, or wavelength specific. A radiation absorbing material or a radiation emitting material may be included. There may be a plurality of electrically modulated material layers. Different layers or regions of electrically modulated material may have different properties or colors. Furthermore, the properties of the various layers may be different from one another. For example, one layer can be used to view or display information in the visible light range, whereas the second layer responds to or emits ultraviolet light. Alternatively, the invisible layer can be composed of a non-electrically modulated material having radiation absorbing or emitting properties. A feature of the electrically modulated material employed in the context of the present invention is that it does not require power to maintain display content.

  A preferred thermosensitive material for use with the curing device is a liquid crystal material. The liquid crystal material may be nematic (N), chiral nematic (N *), or smectic depending on the arrangement of the molecules in the mesophase. Chiral nematic liquid crystal means a type of liquid crystal with a finer pitch than twisted nematic and super twisted nematic. Chiral nematic liquid crystals are so named because such liquid crystal formulations are generally obtained by adding chiral agents to host nematic liquid crystals. Chiral nematic liquid crystals to provide a bistable or multistable reflective display that does not require a continuous drive circuit to maintain the display image due to its non-volatile “memory” characteristics, thereby significantly reducing power consumption Can be used. Chiral nematic displays are bistable in the absence of a field, and two stable textures are a reflective planar texture and a weakly scattered focal conic texture. In the case of planar texture, the helical axis of the chiral nematic liquid crystal molecule is substantially perpendicular to the support on which the liquid crystal is arranged. In the focal conic state, the helical axes of the liquid crystal molecules are aligned almost randomly. By adjusting the concentration of the chiral dopant in the chiral nematic material, the pitch length of the molecule and thus the wavelength of the radiation reflected by the molecule can be adjusted. Chiral nematic materials that reflect infrared light are used for scientific research. Commercial displays are most often made from chiral nematic materials that reflect visible light. Some known LCD devices include a chemically etched transparent conductive layer that covers a glass substrate as described in US Pat. No. 5,667,853.

  Current chiral nematic liquid crystal materials usually contain at least one nematic host in combination with a chiral dopant. Suitable chiral nematic liquid crystal compositions preferably have a positive dielectric anisotropy and comprise the chiral material in an amount effective to form a focal conic texture and a twisted planar texture. Chiral nematic liquid crystal materials are preferred because of their excellent reflective properties, bistability and gray scale memory. A chiral nematic liquid crystal is typically a mixture of an amount of nematic liquid crystal and a chiral material sufficient to form the desired pitch length.

  Chiral nematic liquid crystal materials and cells, and polymer-stabilized chiral nematic liquid crystals and cells are known to those skilled in the art, e.g., U.S. Patent No. 5,695,682, U.S. Patent Application No. 07 / 969,093, ibid. 08 / 057,662, Yang et al., Appl. Phys. Lett. 60 (25) 3102-04 (1992), Yang et al., J. Appl. Phys. 76 (2), 1331 (1994), It is described in International Patent Application No. PCT / US92 / 09367 and International Patent Application No. PCT / US92 / 03504.

  Figure 1 utilizes a folding mirror, a coalescing mirror, reduces heat through an infrared mirror / absorber with a visible spectral filter in the optical path, and isolates the lamp chamber from the transport mechanism that holds the substrate Thus, a system for merging two optical paths into a single path is shown. The modeling data for the system of FIG. 1 shows 22-45% system efficiency. As shown in FIG. 1, according to the present invention, an illumination lamp assembly combines two lamp light spectra into one optical path. The ultraviolet and infrared spectra are generated from lamps (11) and (16), and the light has some dichroic coating to absorb some infrared energy from the lamps but transmit most of the UV spectrum It is transmitted to the folding mirror (12) via reflectors (10) and (17). The folding mirror, which may have a cooling means and may also have a dichroic coating that absorbs some IR, transmits two optical paths to the coalescing mirror (13), and the coalescing mirror has two optical paths. Merge them into one. The coalescing mirror (13) can have a spherical or parabolic surface to improve the efficiency of the amount of transmitted light. The uniting mirror may have means for independently adjusting the light incident angle from the folding mirror (12) to the substrate (15). The combined light is then transmitted through an optional optical filter (14) mounted on the frame (36) prior to exposure of the substrate (15), where infrared or visible radiation is removed. By drawing cooling air into the upper frame (30) and removing the heated air through the upper chamber exhaust port (33) and allowing the desired spectrum of the optical path to reach the substrate (15) On the other hand, by separating the upper chamber (30) from the lower chamber (31) by the optical filter (14) placed on the frame (36), the heat generated by the lamp quartz enclosure is reduced. The substrate (15) is passed through the combined optical path via a moving perforated transport belt (34) that slides over a heat exchanger with holes (37), and the heat exchanger is placed in the lower chamber ( The substrate is held on the belt by the vacuum generated by the exhaust vacuum supply section (32) of 31).

  FIG. 2 shows a system for combining two optical paths into a single path by using a folding mirror, a refractive element, and a combining mirror. Heat is reduced by isolating the lamp chamber through infrared mirrors / absorbers and visible spectral filters in the optical path and from the transport mechanism that holds the substrate. The modeling data for the system of Figure 2 shows a system efficiency of nearly 28%. In FIG. 2, an illumination lamp assembly combines two lamp light spectra into one optical path in accordance with the present invention. The ultraviolet and infrared spectra are generated from lamps (11) and (16), and the light has some dichroic coating to absorb some infrared energy from the lamps but transmit most of the UV spectrum It is transmitted to the folding mirror (12) via reflectors (10) and (17). The folding mirror, which may have a cooling means and may also have a dichroic coating that absorbs some IR, transmits the two optical paths to the refractive element (20) that serves the purpose of the field lens, The element then transmits the two optical paths to the coalescing mirror (13). The coalescing mirror (13) can have a spherical or parabolic surface to improve the efficiency of the amount of transmitted light. The combining mirror (13) can also have means for independently adjusting the light incident angle from the refractive element (20) to the substrate (15). The combined light is then transmitted through an optional filter (14) mounted on the frame (36) prior to exposure of the substrate (15) where infrared or visible radiation is removed. By drawing cooling air into the upper frame (30) and removing the heated air through the upper chamber exhaust port (33), and allowing the intended spectrum of light to reach the substrate (15) On the other hand, by separating the upper chamber (30) from the lower chamber (31) by the optical filter (14) placed on the frame (36), the heat generated by the lamp quartz enclosure is reduced. The substrate (15) is passed through the combined optical path via a perforated transport belt (34) that slides over a heat exchanger with holes (37), and the heat exchanger is placed in the lower chamber (31). The substrate is held on the belt by the vacuum generated by the exhaust / vacuum supply unit (32). In one preferred embodiment, the improved chamber configuration limits the amount of heat from the lamp to the support by redirecting the lamp supply cooling air to the new upper chamber exhaust port. The upper / lower chamber isolation assembly can help isolate the upper and lower chambers and also reduce the amount of heat sensed by the substrate on the transport belt.

  FIG. 3 shows a system for merging two optical paths into a single path by positioning / angling the lamp assembly so that the combined lamp spectrum reaches the substrate. Cooling air is drawn into the upper frame (30) through the infrared mirror / absorber and visible spectral filter in the optical path and the heated air is removed through the upper chamber exhaust port (33) And by isolating the lamp chamber from the transport mechanism that holds the substrate, heat is reduced. The modeling data for the system of Figure 3 shows a system efficiency of nearly 24%. In FIG. 3, an illumination lamp assembly combines two lamp light spectra into one optical path in accordance with the present invention. Ultraviolet and infrared spectra are generated from the lamps (11) and (16), and the light is transmitted through an optional filter (14) mounted on the frame (36) prior to exposure of the substrate (15). In this place, infrared or visible rays are removed. Isolate the upper chamber (30) from the lower chamber (31) by the optical filter (14) mounted on the frame (36) while allowing the desired spectrum of light to reach the substrate (15) By doing so, the heat generated by the lamp quartz enclosure is reduced. The substrate (15) is passed through the combined optical path via a perforated transport belt (34) that slides over a heat exchanger with holes (37), and the heat exchanger is placed in the lower chamber (31). The substrate is held on the belt by the vacuum generated by the exhaust / vacuum supply unit (32). This embodiment provides a means of isolating the upper chamber (8) from the lower chamber (9), thereby preventing cooling air heated by the lamp quartz from reaching the transport belt (34). This embodiment also incorporates an IR-reflecting dichroic coating on some of the quartz plates (10), and also to further reduce heat to the substrate on the transport belt (34) Incorporating a selective visible light dichroic coating (filter) on the plate (10) provides a means to reduce the infrared heat generated by the lamp from reaching the transport belt. In addition, further heat reduction is achieved by redirecting heat from the lamp to the upper chamber exhaust port (33).

  FIG. 4 shows a system for merging two light paths into a single path by arranging the lamp assembly in a horizontal direction and directing the two light paths to the coalescing mirror. Cooling air is drawn into the upper frame (30) through the infrared mirror / absorber and visible spectral filter in the optical path and the heated air is removed through the upper chamber exhaust port (33) And by isolating the lamp chamber from the transport mechanism that holds the substrate, heat is reduced. The modeling data for the system in Figure 4 shows a system efficiency of nearly 40%. In FIG. 4, an illumination lamp assembly combines two lamp light spectra into one optical path in accordance with the present invention. The ultraviolet and infrared spectra are generated from lamps (11) and (16), and the light has some dichroic coating to absorb some infrared energy from the lamps but transmit most of the UV spectrum Is transmitted to the combining mirror (13) via the reflectors (10) and (17). The coalescing mirror can have a spherical or parabolic surface to improve the efficiency of the amount of transmitted light. The coalescing mirror (13) can also have means for independently adjusting the light incident angle from the lamp reflectors (10) and (17) to the substrate (15). The combined light is then transmitted through an optional optical filter (14) mounted on the frame (36) prior to exposure of the substrate (15), where infrared or visible radiation is removed. Isolate the upper chamber (30) from the lower chamber (31) by the optical filter (14) mounted on the frame (36) while allowing the desired spectrum of light to reach the substrate (15) By doing so, the heat generated by the lamp quartz enclosure is reduced. The substrate (15) is passed through the combined optical path via a perforated transport belt (34) that slides over a heat exchanger with holes (37), and the heat exchanger is placed in the lower chamber (31). The substrate is held on the belt by the vacuum generated by the exhaust vacuum supply unit (32).

  FIG. 5 is a schematic diagram showing a dual lamp UV curing unit commercially available from Fusion UV® according to the prior art. The system consists of a model LC-6B conveyor assembly and two F300S UV curing lamp irradiator assemblies. Ultraviolet and infrared spectra are generated from the lamps in the UV lamp assembly (2), and cooling air is supplied from the inlet (1) with filter. The lamp heated air then enters the transport assembly chamber (3), passes through the perforated transport belt (34) containing the substrate to be cured, then the vacuum supply / lamp exhaust port (5), and the conveyor Exit the conveyor assembly through the tunnel entrance and exit.

  FIG. 6 shows a preferred system for merging two light paths into a single path by arranging the lamp assembly in a horizontal direction and directing the two light paths to a coalescing mirror. Each of the beams from the two lamps reflects an angled mirror or special IR absorbing (hot) mirror, passes through a set of arbitrary filters, and passes through any set of filters so that the beams merge and strike the substrate simultaneously. It is directed to the substrate through a mechanical on / off valve. Cooling air is drawn into the upper frame (30) through the infrared mirror / absorber and visible spectral filter in the optical path and the heated air is removed through the upper chamber exhaust port (33) And by isolating the lamp chamber from the transport mechanism holding the substrate, preferably using a shutter-type mechanism, heat is reduced. In FIG. 6, an illumination lamp assembly combines two lamp light spectra into one optical path in accordance with the present invention. The ultraviolet and infrared spectra are generated from lamps (11) and (16), and the light has some dichroic coating to absorb some infrared energy from the lamps but transmit most of the UV spectrum Is transmitted to the combining mirror (13) via the reflectors (10) and (17). The coalescing mirror can have a spherical or parabolic surface to improve the efficiency of the amount of transmitted light. The coalescing mirror (13) can also have means for independently adjusting the light incident angle from the lamp reflectors (10) and (17) to the substrate (15). In a preferred embodiment, the coalescing mirror has a coating that absorbs most of the IR spectrum and reflects most of the UV. Funneled mirrors (38) and (39) increase the exposure by redirecting light that otherwise fails to target the substrate. The combined light is then transmitted through an optional optical filter (14) mounted on the frame (36) where infrared or visible radiation is removed and then mechanically exposed before the substrate (15) is exposed. Shut off (40), eg through a shutter. Isolate the upper chamber (30) from the lower chamber (31) by the optical filter (14) mounted on the frame (36) while allowing the desired spectrum of light to reach the substrate (15) By doing so, the heat generated by the lamp quartz enclosure is reduced. The optical filter / frame device may further include a shutter to further isolate the light source from the substrate. The substrate (15) is passed through the combined optical path via a perforated transport belt (34) that slides over a heat exchanger with holes (37), and the heat exchanger is placed in the lower chamber (31). The substrate is held on the belt by the vacuum generated by the exhaust vacuum supply unit (32).

  Figure 8 shows the Fusion UV conveyor assembly and dual lamp irradiator system. This figure shows a variation of the system having a separate isolated exhaust port for lamp cooling air exhaust and an upper / lower chamber isolation assembly. The improved chamber configuration limits the amount of heat from the lamp to the support by redirecting the lamp supply cooling air (1) to the new upper chamber exhaust port (6). The upper / lower chamber isolation assembly (7) isolates the upper and lower chambers and helps to reduce the amount of heat sensed by the substrate on the transport belt (34).

  The present invention can be used to cure any UV-sensitive material. Preferably, the present invention cures materials that are difficult to cure using conventional techniques due to the presence of particles, flakes, or droplets in the UV curable material, or the thermal sensitivity of the UV curable material or substrate. Used to make

  In the method of the present invention, a support, panel, or object containing a UV curable material is provided, which is then exposed to a cured assembly comprising at least two light sources, and the respective spectra of these light sources. Are combined into a single optical path. Preferably, the method also includes removing a portion of the infrared energy from the optical path by absorbing IR on a surface that reflects the UV spectrum. In the most preferred case of the heat sensitive UV curable material, sufficient IR energy is removed to reduce or eliminate the heat transfer of the heat sensitive curable layer or the heat sensitive layer associated with the curable layer. The method can include opening a shutter between the material and the light source prior to exposing the material on the substrate.

  The method can include an additional mirror to collect stray light and funnel it toward the target area to be cured. This method can also use a filter through which a combined beam or individual beam passes that removes part of the visible or IR light. This method uses a mechanical shut-off mechanism, such as a rotary valve, slide gate, or any of a number of configurations to stop the light from reaching the target instead of turning the light source on and off when not desired You can also.

  One particularly preferred application of the invention relates to the production of flexible cholesteric liquid crystal displays. As used herein, a “liquid crystal display” (LCD) is a type of flat panel display used in various electronic devices. At a minimum, an LCD includes a substrate, at least one conductive layer, and a liquid crystal layer. The LCD may include two polarizer material sheets and a liquid crystal solution located between the polarizer sheets. The polarizer material sheet may include a substrate made of glass or transparent plastic. The LCD may include a functional layer.

  Liquid crystal (LC) is used as an optical switch. The substrate is typically manufactured with a transparent conductive electrode within which an electrical “drive” signal is coupled. The drive signal induces an electric field that can cause a phase change or state change in the LC material, and the LC thus exhibits different light reflection characteristics depending on its phase and / or state.

  The present invention preferably employs a chiral nematic liquid crystal composition dispersed in a continuous matrix as the light modulating layer. Such materials are referred to as “polymer dispersed liquid crystal” materials, or “PDLC” materials. Such materials can be formed by a variety of methods. For example, Doane et al. (Applied Physics Letters, 48, 269 (1986)) discloses a PDLC containing approximately 0.4 mm droplets of nematic liquid crystal 5 CB in a polymer binder. A phase separation method is used to prepare this PDLC. A solution containing the monomer and liquid crystal is filled into the display cell and the material is then polymerized. When polymerized, the liquid crystal becomes immiscible and nucleates to form droplets. West et al. (Applied Physics Letters, 63, 1471 (1993)) discloses a PDLC containing a chiral nematic mixture in a polymer binder. Again, a phase separation method is used to prepare PDLC. The liquid crystal material and polymer (hydroxy functionalized polymethylmethacrylate) are dissolved in a common organic solvent toluene together with a crosslinker for the polymer and applied onto an indium tin oxide (ITO) substrate. When toluene is evaporated at high temperature, a dispersion of liquid crystal material in a polymer binder is formed.

  The liquid crystal material can be formed by a method known to those skilled in the art, for example, an emulsification method or a phase separation method. In a preferred embodiment, the liquid crystal material can be processed using a limited agglomeration process to form a liquid crystal material emulsion having a uniform size. Such a method is disclosed in US patent application Ser. No. 10 / 095,379. This method can be carried out by homogenizing the liquid crystal material in the presence of finely divided silica and an agglomeration limiting material such as LUDOX from duPont Corporation. Accelerator materials can be added to the aqueous bath to drive the colloidal particles to the liquid-liquid interface. In a preferred embodiment, a copolymer of adipic acid and 2- (methylamino) ethanol can be used as an accelerator in the water bath. To form liquid crystal domains with a size of less than 1 micron, the liquid crystal material can be dispersed using ultrasound. When the ultrasonic energy is removed, the liquid crystal material aggregates into uniform size domains. The ratio of minimum domain size to maximum domain size preferably varies by about 1: 2. By varying the amount of silica and copolymer relative to the liquid crystal material, it is possible to produce an average domain size emulsion with an average diameter of about 1, 3 and 8 microns as measured microscopically. These emulsions can be diluted in gelatin solution for subsequent application.

  Preferably, the domain is a flattened sphere and on average has a thickness that is significantly less than the length, preferably at least 50% less. More preferably, the ratio of domain thickness (depth) to length is 1: 2 to 1: 6 on average. Domain flattening can be achieved by proper blending of the coating and sufficiently rapid drying. The preferred average diameter of the domain is 2-30 microns. The preferred thickness of the imaging layer is 10 to 150 microns when first applied and 2 to 20 microns when dried.

  A flattened domain of a liquid crystal material can be defined as having a major axis and a minor axis. In the preferred embodiment of the display or display sheet, the major axis size is greater than the cell (or imaging layer) thickness for most of the domain. Such dimensional relationships are shown in US Pat. No. 6,061,107.

  In the preferred embodiment, the contrast of the display is maximized by using only a substantial monolayer of N * LC domains. The term “substantially monolayer” is used herein in the direction perpendicular to the display plane at most points of the display, preferably more than 75% of the point (area) of the display, most preferably the display. 90% or more of this point (area) means that only a single domain layer is sandwiched between the electrodes. In other words, in most cases, a small fraction (preferably less than 10%) of the display point (or area) compared to the amount of display point (or area) that has only a single domain between the electrodes. However, in the direction perpendicular to the display plane, there are more domains (two or more domains) between the electrodes than a single domain.

  The amount of material required for a single layer can be accurately determined by calculating based on individual domain sizes, assuming a fully hermetically packed domain arrangement. In practice, defects that cause gaps and some non-uniformity due to overlapping droplets or domains can occur. On this basis, the calculated amount is preferably less than 150% of the amount required for single layer domain coating, preferably no more than 125% of the amount required for single layer domain coating, more preferably 110% or less of the amount required for a single layer. Furthermore, viewing angle and broadband characteristics can be improved by appropriately selecting differently doped domains based on the applied droplet geometry and Bragg reflection conditions.

  The liquid crystal layer can also contain other components. For example, the color is introduced by the liquid crystal material itself, but pleochroic dyes can be added to enhance or change the color reflected by the cell. Similarly, additives such as fumed silica can be dissolved in the liquid crystal mixture to adjust the stability of various chiral nematic textures. Dye in amounts of 0.25% to 1.5% can also be used.

  In conjunction with the present invention, at least one conductive layer can be utilized. For higher conductivity, the conductive layer may include a silver based layer. The silver-based layer contains only silver or different elements such as aluminum (Al), copper (Cu), nickel (Ni), cadmium (Cd), gold (Au), zinc (Zn), Magnesium (Mg), tin (Sn), indium (In), tantalum (Ta), titanium (Ti), zirconium (Zr), cerium (Ce), silicon (Si), lead (Pb) or palladium (Pd) Contains silver. In a preferred embodiment, the conductive layer comprises at least one of gold, silver and a gold / silver alloy, for example a silver layer with a thinner gold layer applied on one or both sides. See WO99 / 36261 pamphlet by Polaroid Corporation. In another embodiment, the conductive layer may include a silver alloy layer, eg, a silver layer with an indium cerium oxide (InCeO) layer applied on one or both sides. See U.S. Pat. No. 5,667,853.

  The conductive layer can be formed in a vacuum environment using materials such as aluminum, tin, silver, platinum, carbon, tungsten, molybdenum or indium. These metal oxides can be used to darken the patternable conductive layer. The metallic material can be excited by energy resulting from resistive heating, cathode arc, electron beam, sputtering or magnetron excitation. The conductive layer can include a coating made of tin oxide or indium tin oxide so that the layer is transparent. Two or more conductive layers can also be provided.

Current chiral nematic liquid crystal materials usually contain at least one nematic host in combination with a chiral dopant. In general, the nematic liquid crystal phase consists of one or more mesogenic components combined to provide useful composite properties. Many such materials are commercially available. The nematic component of the chiral nematic liquid crystal mixture may consist of any suitable nematic liquid crystal mixture or composition having suitable liquid crystal properties. Nematic liquid crystals suitable for use in the present invention are preferably nematic or nematogenic substances such as the known classes of azoxybenzene, benzylideneaniline, biphenyl, terphenyl, phenyl or cyclohexylbenzoates, phenyl or cyclohexyl esters of cyclohexanecarboxylic acid. Cyclohexyl benzoic acid phenyl or cyclohexyl ester; cyclohexyl cyclohexane carboxylic acid phenyl or cyclohexyl ester; benzoic acid, cyclohexane carboxylic acid, and cyclohexyl cyclohexane carboxylic acid cyclohexyl phenyl ester; phenyl cyclohexane; cyclohexyl biphenyl; phenyl cyclohexyl cyclohexane; cyclohexyl cyclohexane; Cyclohexyl Cyclohexyl cyclohexyl cyclohexene; 1,4-bis-cyclohexyl benzene; 4,4-bis-cyclohexyl biphenyl; phenyl- or cyclohexyl pyrimidine; phenyl- or cyclohexyl pyridine; phenyl- or cyclohexyl pyridazine; phenyl- or cyclohexyl dioxane; Or cyclohexyl-1,3-dithiane; 1,2-diphenylethane; 1,2-dicyclohexylethane; 1-phenyl-2-cyclohexylethane; 1-cyclohexyl-2- (4-phenylcyclohexyl) ethane; 1-cyclohexyl- 2 ', 2-biphenylethane; 1-phenyl-2-cyclohexylphenylethane; optionally halogenated stilbene; benzylphenyl ether; tolan; substituted cinnamic acids and esters; and a further class of nematic or menatogeni Consisting of the compounds of low molecular weight selected from click material. The 1,4-phenylene group in these compounds can also be mono- or difluorinated laterally. The liquid crystal material of this preferred embodiment is based on this type of achiral compound. The most important compounds possible as components of these liquid crystal materials can be characterized by the following formula R′-XYZ-R ″: In this formula, X and Z, which may be the same or different, in each case are independently of each other -Phe-, -Cyc-, -Phe-Phe-, -Phe-Cyc-, -Cyc- A divalent radical from a group formed by Cyc-, -Pyr-, -Dio-, -B-Phe- and -B-Cyc-; Phe is unsubstituted or fluorine-substituted 1,4-phenylene Cyc is trans-1,4-cyclohexylene or 1,4-cyclohexenylene, Pyr is pyrimidine-2,5-diyl or pyridine-2,5-diyl, Dio is 1,3-dioxane -2,5-diyl and B is 2- (trans-1,4-cyclohexyl) ethyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, or 1,3-dioxane-2, 5-Diyl. Y in these mixtures represents the following divalent groups -CH = CH-, -C≡C-, -N = N (O)-, -CH = CY'-, -CH = N (O)-, -CH ₂ -CH _2- , -CO-O-, -CH ₂ -O-, -CO-S-, -CH ₂ -S-, -COO-Phe-COO- or a single bond, Y ' Is halogen, preferably chlorine or —CN; R ′ and R ″ are in each case, independently of one another, alkyl, alkenyl, alkoxy, alkenyloxy having 1 to 18 carbon atoms, preferably 1 to 12 carbon atoms. , Alkanoyloxy, alkoxycarbonyl, or alkoxycarbonyloxy, or one of R ′ and R ″ is —F, —CF ₃ , —OCF ₃ , —Cl, —NCS, or —CN. In most of these compounds, R ′ and R ″ in each case, independently of one another, are alkyls, alkenyls or alkoxys having different chain lengths, and the sum of carbon atoms in the nematic medium is 2-9, Preferably it is 2-7. The nematic liquid crystal phase is typically composed of 2 to 20, preferably 2 to 15 components. The above list of materials is not intended to be comprehensive or limiting. This list discloses various representative materials or mixtures suitable for use. These mixtures contain active elements in the electro-optical liquid crystal composition.

  Suitable chiral nematic liquid crystal compositions preferably have a positive dielectric anisotropy and comprise the chiral material in an amount effective to form a focal conic texture and a twisted planar texture. Chiral nematic liquid crystal materials are preferred because of their excellent reflective properties, bistability and gray scale memory. A chiral nematic liquid crystal is typically a mixture of an amount of nematic liquid crystal and a chiral material sufficient to form the desired pitch length. Suitable commercial nematic liquid crystals include, for example, E7, E48, E44, E31, E80, TL202, TL203, TL204 and TL205 manufactured by E. Merck (Darmstadt, Germany). Chiral nematic materials may include, for example, one or more of the following materials obtained from Merck Ltd .: BL061, BL100, BL101, BL087, BL118, and BL036. Nematic liquid crystals having a positive dielectric anisotropy, particularly cyanobiphenyl, are preferred, but virtually any nematic liquid crystal known to those skilled in the art, including nematic liquid crystals having a negative dielectric anisotropy, is suitable for use in the present invention. obtain. The chiral nematic liquid crystal may be Merck BL112, BL126, BL-03, BL-048, or BL-033 available from EM Industries of Hawthorne, NY. Other suitable materials may include ZLI-3308, ZLI-3273, ZLI-5048-000, ZLI-5049-100, ZLI-5100-100, ZLI-5800-000, MCL-6041-100. Other light reflective or light diffusive, electrically manipulated materials such as microencapsulated electrophoretic materials in oil can also be applied. Examples of nematic hosts are mixtures containing 5CB or MBBA.

  Chiral dopants added to the nematic mixture to induce a helical twist of the mesophase and thereby allow reflection of visible light can be formed from any useful structural class. The dopant is selected according to several properties including, among other things, chemical compatibility with the nematic host, helical torsional force, temperature sensitivity, and light fastness. Many chiral dopant classes such as G. Gottarelli and G. Spada, Mol. Cryst. Liq. Crys., 123, 377 (1985), G. Spada and G. Proni, Enantiomer, 3, 301 (1998) and References listed therein are known to those skilled in the art. Well-known typical dopant classes include 1,1-binaphthol derivatives, isosorbide and similar isomannide esters as disclosed in U.S. Patent 6,217,792, U.S. Patent 6,099,751. TADDOL derivatives as disclosed, and by T. Welter et al., Filed Aug. 29, 2003, entitled "Chiral Compound And Compositions Containing The Same" Pending spiroindane esters as disclosed in US patent application Ser. No. 10 / 651,692 are included.

  The pitch length of the liquid crystal material can be adjusted based on the following equation (1).

λ _max = n _av p ₀

In the above formula, λ _max is the peak reflection wavelength, that is, the wavelength at which the reflectance is the maximum value, n _av is the average refractive index of the liquid crystal material, and p ₀ is the natural _value of the chiral nematic helix. The pitch length. The definition of chiral nematic helix and pitch length and its measurement method is described in the book Blinov, LM, “Electro-Optical and Magneto-Optical Properties of Liquid Crystals” (John Wiley & Sons Ltd. 1983) is known to those skilled in the art. The pitch length is modified by adjusting the concentration of the chiral material in the liquid crystal material. For most concentrations of chiral dopant, the pitch length induced by the dopant is inversely proportional to the concentration of the dopant. The proportionality constant is given by equation (2) below.

p ₀ = 1 / (HTP.c)

  Where c is the concentration of the chiral dopant and HTP is a proportionality constant.

  For some applications, it is desirable to have an LC mixture that exhibits a strong helical twist and thereby a short pitch length. For example, in a liquid crystal mixture used in a selectively reflective chiral nematic display, the pitch is selected so that the maximum wavelength reflected by the chiral nematic helix is in the visible range. It must be. Other possible applications are polymer films with a chiral liquid crystal phase for optical elements, such as chiral nematic broadband polarizers, filter arrays, or chiral liquid crystal retardation films. Among these are active and passive optical elements or color filters and liquid crystal displays such as STN, TN, AMD-TN, temperature compensated, polymer-free or polymer-stabilized chiral nematic texture (PFCT, PSCT) displays. is there. Possible display industry applications include notebook and desktop computers, instrument panels, video game consoles, video phones, mobile phones, handheld PCs, PDAs, e-books, video cameras, satellite navigation systems, shops and supermarket prices Includes ultra-lightweight, flexible and inexpensive displays for lighting systems, road signs, information displays, smart cards, toys, and other electronic devices.

  The liquid crystal material can preferably be fabricated using a limited coalescence method to form a uniform size emulsion of the liquid crystal material. This method can be carried out by homogenizing the liquid crystal material in the presence of finely divided silica and an agglomeration limiting material such as LUDOX from duPont Corporation. Accelerator materials can be added to the aqueous bath to drive the colloidal particles to the liquid-liquid interface. In a preferred embodiment, a copolymer of adipic acid and 2- (methylamino) ethanol can be used as an accelerator in the water bath. To form liquid crystal domains with a size of less than 1 micron, the liquid crystal material can be dispersed using ultrasound. When the ultrasonic energy is removed, the liquid crystal material aggregates into uniform size domains. The ratio of minimum domain size to maximum domain size preferably varies by about 1: 2. By varying the amount of silica and copolymer relative to the liquid crystal material, it is possible to produce an average domain size emulsion with an average diameter of about 1, 3 and 8 microns as measured microscopically. These emulsions can be diluted in gelatin solution for subsequent application.

  Control of the liquid crystal droplet size is extremely difficult. This is because such materials have the property of continuously agglomerating into droplets that continue to increase in size until a single phase occurs. In preparing a photographic element containing a layer having liquid crystal droplets, the size of the liquid crystal droplets, and the uniformity of the droplet size, is related to photographic image quality and the apparatus in which the photographic element is employed, such as a camera and a photograph. It has been found that this is a desirable parameter with respect to the scratch resistance of the photographic element when in contact with other parts such as processing equipment. Specific embodiments are shown in the aforementioned co-pending US Pat. No. 5,529,891.

  The liquid crystal droplets described herein form a discontinuous phase of liquid crystal droplets in a continuous aqueous phase containing a particle suspension stabilizer, reduce the liquid crystal droplet size, and with respect to the droplet surface Prepared by limiting the aggregation of the droplets by the action of a particle suspension stabilizer.

  In one embodiment, the liquid crystal droplets can be formed by a limited agglomeration method, where the liquid crystal is dissolved in a solvent suitable for this method, which is established by the droplet size limiting aggregation. And then removed by evaporation. In the case of the second embodiment, a permanent solvent can be mixed with the liquid crystal. This mixture can be dispersed in an aqueous medium, and the size of the droplets is formed by limiting aggregation by the action of a suspension stabilizer. Permanent solvents with higher surface energy remain in the droplets and thus avoid the evaporation step as in the procedure described above. Either of these methods results in a narrow particle size distribution and the average particle size of the droplets is controlled by the amount of particle suspension stabilizer employed in the preparation of the dispersion. Thus, the particular liquid crystal employed can generally be mixed with a volatile or permanent solvent and then dispersed in an aqueous medium containing the particle suspension stabilizer and accelerator. The purpose of the accelerator is to drive the particle suspension stabilizer to the interface between the liquid crystal droplet and the aqueous medium. In order to reduce the particle size of the liquid crystal droplets below the final desired size, the dispersion of liquid crystal droplets in an aqueous medium can be reinforced by any suitable device including high speed agitation, ultrasonic device, and homogenizer. Can be mixed. In this case, the presence of the particle suspension stabilizer controls the level of aggregation that takes place until equilibrium is reached and until the particle size no longer grows. In the case of a preparation containing a volatile solvent, the solvent can then be removed by raising the temperature above the vaporization temperature of the solvent. The droplets can be employed in preparing a coating composition for use in preparing an imaging element. When using a permanent solvent, droplets containing the permanent solvent are used directly in the preparation of the coating composition.

  In order to provide a formulation suitable for applying a layer containing liquid crystal droplets, a dispersion prepared by any of the above methods is combined with a hydrophilic colloid and gelatin is a preferred material. In order to prevent removal of the particle suspension stabilizer from the liquid crystal droplets, a surfactant may be included with the liquid crystal dispersion prior to the addition of gelatin. The surfactant helps to prevent further aggregation of the liquid crystal droplets.

  Suitable hydrophilic binders include both naturally occurring and synthetic materials, ie naturally occurring materials such as proteins, protein derivatives, cellulose derivatives (eg cellulose esters), gelatin and gelatin derivatives, polysaccharides and caseins, and synthetic water permeates. Colloids such as poly (vinyl lactam), acrylamide polymers, poly (vinyl alcohol) and derivatives thereof, hydrolyzed polyvinyl acetate, polymers of alkyl and sulfoalkyl acrylates and methacrylates, polyamides, polyvinyl pyridine, acrylic acid polymers, maleic anhydride copolymers , Polyalkylene oxide, methacrylamide copolymer, polyvinyl oxazolidinone, maleic acid copolymer, vinyl amine copolymer, methacrylic acid copolymer, acryloyl Alkoxyalkyl acrylates and methacrylates include, vinylimidazole copolymers, vinyl sulfide copolymers, and homopolymer or copolymers containing styrene sulfonic acid. Gelatin is preferred.

  In one embodiment, the liquid crystal is dispersed in an aqueous bath containing a water soluble binder material such as deionized gelatin, polyvinyl alcohol (PVA) or polyethylene oxide (PEO). Such compounds can be machine coated in equipment associated with photographic film. It is desirable that the binder has a low ion content. The presence of such ions in the binder prevents an electric field from being generated across the dispersed liquid crystal material. In addition, the ions in the binder move in the presence of an electric field and can chemically damage the light modulation layer. Liquid crystals and gelatin emulsions are applied to a thickness of 5-30 microns to optimize the optical properties of the light modulating layer. The coating thickness, the size of the liquid crystal domain, and the concentration of the domain of the liquid crystal material are configured to optimize the optical properties. Conventionally, liquid crystal dispersions are implemented using a shear mill or other mechanical separation means to form liquid crystal domains within the light modulation layer.

The LCD contains at least one transparent conductive layer. The conductive layer may include other metal oxides, indium oxide, titanium dioxide, cadmium oxide, gallium indium oxide, niobium pentoxide, and tin dioxide. See WO99 / 36261 pamphlet by Polaroid Corporation. In addition to the primary oxide, such as ITO, the at least one conductive layer may include secondary metal oxides, such as oxides of cerium, titanium, zirconium, hafnium, and / or tantalum. See U.S. Pat. No. 5,667,853 to Fukuyoshi et al. (Toppan Printing Co.). Examples of other transparent conductive oxides include ZnO ₂ , Zn ₂ SnO ₄ , Cd ₂ SnO ₄ , Zn ₂ In ₂ O ₅ , MgIn ₂ O ₄ , Ga ₂ O ₃ --In ₂ O ₃ , or TaO ₃ is mentioned. The conductive layer can be formed by, for example, low temperature sputtering techniques, or direct current sputtering techniques, such as DC-sputtering or RF-DC sputtering, depending on the material or materials of the underlying layer. The conductive layer may be a transparent conductive layer made of tin oxide or indium tin oxide (ITO) or polythiophene, with ITO being the preferred material. Typically, the conductive layer is sputtered onto the substrate to a resistance of less than 250 ohms / square. Alternatively, the conductive layer may be an opaque electrical conductor formed from a metal, such as copper, aluminum or nickel. If the conductive layer is an opaque metal, this metal may be a metal oxide for forming the light absorbing conductive layer.

  Indium tin oxide (ITO) is a preferred conductive material. This is because ITO is a cost effective conductor with good environmental stability, up to 90% transmission, and a minimum 20 ohm / square resistivity. An example of a preferred ITO layer has a% T of 80% or more in the visible region of light, ie above 400 nm to 700 nm, so that the film is useful for display applications. In a preferred embodiment, the conductive layer includes a polycrystalline low temperature ITO layer. The ITO layer is preferably 10-120 nm thick, or 50-100 nm thick, so as to achieve a resistivity of 20-60 ohms / square on the plastic. An example of a preferred ITO layer is 60-80 nm thick.

  The conductive layer is preferably patterned. The conductive layer is preferably patterned into a plurality of electrodes. Patterned electrodes can be used to form LCD devices. In another embodiment, two conductive substrates are placed facing each other and a cholesteric liquid crystal is placed between them to form a device. The patterned conductive layer may have various dimensions. Examples of dimensions can include a line width of 10 microns, a distance between lines, ie, an electrode width of 200 microns, a cut depth, ie, a thickness of 100 nanometers of the ITO conductor. ITO thicknesses on the order of over 60, 70 and 100 nanometers are possible.

  The display can also contain a second conductive layer applied to the surface of the light modulation layer. The second conductive layer desirably has sufficient conductivity to carry an electric field throughout the light modulation layer. The second conductive layer can be formed in a vacuum environment using materials such as aluminum, tin, silver, platinum, carbon, tungsten, molybdenum or indium. These metal oxides can be used to darken the patternable conductive layer. The metallic material can be excited by energy resulting from resistive heating, cathode arc, electron beam, sputtering or magnetron excitation. The second conductive layer can include a coating made of tin oxide or indium tin oxide so that the layer is transparent. Alternatively, the second conductive layer may be a printed conductive ink.

  To make the conductivity higher, the second conductive layer contains only silver or different elements such as aluminum (Al), copper (Cu), nickel (Ni), cadmium (Cd), gold (Au), zinc (Zn), magnesium (Mg), tin (Sn), indium (In), tantalum (Ta), titanium (Ti), zirconium (Zr), cerium (Ce), silicon (Si), lead A silver base layer containing silver containing (Pb) or palladium (Pd) may be included. In a preferred embodiment, the conductive layer comprises at least one of gold, silver and gold / silver alloy, for example a silver layer with a thinner gold layer applied on one or both sides. See WO99 / 36261 pamphlet by Polaroid Corporation. In another embodiment, the conductive layer may include a silver alloy layer, eg, a silver layer with an indium cerium oxide (InCeO) layer applied on one or both sides. See U.S. Pat. No. 5,667,853.

The LCD may also include at least one “functional layer” between the conductive layer and the substrate. The functional layer may include a protective layer or a barrier layer. The functional layer is a UV curable layer. Preferred barrier layers can act as gas barriers or moisture barriers and can include SiO _x , AlO _x or ITO. A protective layer, such as an acrylic hard coating, functions to prevent laser light from reaching the functional layer between the protective layer and the substrate, thereby protecting both the barrier layer and the substrate. The functional layer can also serve as an adhesion promoter for the conductive layer to the substrate.

In another aspect, the polymeric support can further include an antistatic layer to manage unwanted charging formed on the sheet or web during roll conveyance or sheet finishing. Since the liquid crystal is switched between states by voltage, a sufficient voltage charge accumulation on the web surface can form an electric field that can switch part of the liquid crystal during discharge. It is well known to those skilled in the art of photographic web-based materials that winding, conveying, slitting, shredding and finishing can cause charging on many web-based substrates. High charging is a particular problem with plastic webs that are conductive on one side but not on the other. Charges accumulate on one side of the web up to the point of discharge and fog may occur as a result of the discharge in photosensitive photographic materials. Fog is an uncontrolled exposure that occurs as a result of a spark caused from a discharge. Similar precautions and electrostatic management are necessary during manufacture or in the end use of liquid crystal displays. In another embodiment of the present invention, the antistatic layer has a surface resistivity of 10 ⁵ to 10 ¹² . Above 10 ¹² , the antistatic layer typically does not allow sufficient charge conduction to prevent charge accumulation to the extent that fog is prevented in photographic systems or is undesirable in liquid crystal displays. It does not allow sufficient charge conduction to prevent point switching. Although layers above 10 ⁵ prevent charging, most antistatic materials are not inherently conductive, and for these materials with higher conductivity than 10 ⁵ , the overall transmission characteristics of the display are usually reduced. There is some color associated with the material to be reduced. The antistatic layer is remote from the highly conductive layer of the ITO and allows the best electrostatic control when it is located on the opposite side of the web substrate from the ITO layer side. The antistatic layer may include the web substrate itself.

  One type of functional layer may be a color contrast layer. The color contrast layer may be a radiation reflecting layer or a radiation absorbing layer. In some cases, the backmost substrate of each display may be preferably painted black. The black paint absorbs infrared rays that reach the back of the display. For stacked cell displays, contrast can be improved by painting the substrate behind the last visible cell in black. The paint is preferably transparent to infrared. This effectively provides a visible cell with a black background that improves contrast and does not change the viewing characteristics of the infrared display. Paints that are transparent in the infrared region, such as black paint, are known to those skilled in the art. For example, many types of black paint used to print characters on computer keys are transparent to infrared. In one embodiment, the light absorber can be disposed on the side facing the incident light. In the fully developed focal conic state, the chiral nematic liquid crystal is transparent and allows incident light to pass through. This incident light is absorbed by the light absorber to form a black image. As the focal conic state evolves gradually, the observer will perceive the reflected light transition to black as the chiral nematic material changes from the planar state to the focal conic state. The transition to the light transmissive state is gradual, and variable reflection levels are possible by changing the low voltage time. These variable levels can be located at the corresponding gray levels, and when the field is removed, the light modulation layer maintains a given optical state indefinitely. This process is more fully discussed in US Pat. No. 5,437,811.

  The color contrast layer may be other colors. In another embodiment, the dark layer includes pulverized non-conductive pigment. The material is ground to less than 1 micron to form a “nanopigment”. Such pigments are effective in absorbing the wavelength of light in very thin layers or “submicron” (less than 1 micron) layers. In a preferred embodiment, the dark layer absorbs all wavelengths of light over the entire visible light spectrum from 400 nanometers to 700 nanometers. The dark layer can also contain one or more pigment dispersions. For example, three different pigments, such as a yellow pigment ground to a median diameter of 120 nanometers, a magenta pigment ground to a median diameter of 210 nanometers, and a cyan pigment ground to a median diameter of 110 nanometers, such as Sunfast® ) Blue Pigment 15: 4 pigment is combined. A mixture of these three pigments produces uniform light absorption over the entire visible spectrum. Suitable pigments are readily available and are configured to be light absorbing over the entire visible spectrum. In addition, suitable pigments are inert and do not carry an electric field.

  Suitable pigments used in the color contrast layer may be any coloring material, and these materials are practically insoluble in the incorporated media. Preferred pigments are organic materials in which carbon is bound to a hydrogen atom and at least one other element such as nitrogen, oxygen and / or transition metals. The hue of an organic pigment is primarily defined by the presence of one or more chromophores, ie, a system of conjugated double bonds in the molecule that are involved in the absorption of visible light. Suitable pigments include those described in Industrial Organic Pigments: Production, Properties, Applications (W. Herbst and K. Hunger, 1993, Wiley Publishers). This document is incorporated herein for reference. Examples of these pigments include azo pigments such as monoazo yellow and orange, diazo, naphthol, naphthol red, azo lake, benzimidazolone, diazo condensates, metal complexes, isoindolinone and isoindoline polycyclic Pigments such as phthalocyanine, quinacridone, perylene, perinone, diketopyrrolo-pyrrole, and thioindigo, and anthriquinone pigments such as anthrapyrimidine, triarylcarbonium and quinophthalone.

  Protective layers useful in the practice of the present invention are well known in many techniques, such as dip coating, rod coating, blade coating, air knife coating, gravure coating, reverse roll coating, extrusion coating, slide coating, and curtain coating. Can be applied in any of the above. The liquid crystal particles and the binder are preferably mixed in a liquid medium to form a coating composition. The liquid medium may be a medium, such as water or other aqueous solution, in which the hydrophilic colloid is dispersed with or without the presence of a surfactant.

  There are alternative display technologies for LCDs that can be used, for example, in flat panel displays. Notable examples are organic light emitting devices (OLEDs) or polymer light emitting devices (PLEDs). These devices consist of several layers, one of which consists of an organic material that can be formed to exhibit electroluminescence by applying a voltage across the device. . OLED devices are typically laminates formed on a substrate, such as glass or plastic polymer. A light emitting layer of luminescent organic solid, as well as an adjacent semiconductor layer, is sandwiched between the anode and the cathode. The semiconductor layer may be a hole injection layer and an electron injection layer. PLEDs can be thought of as OLED variants where the luminescent organic material is a polymer. The light emitting layer can be selected from any of a number of light emitting organic solids, for example, a polymer that is a fluorescent or chemiluminescent organic compound as appropriate. Such compounds and polymers include 8-hydroxyquinolate metal ion salts, trivalent metal quinolate complexes, trivalent metal bridged quinolate complexes, Schiff base divalent metal complexes, tin (IV) metal complexes, metal acetylacetonate complexes. , Organic ligands such as 2-picolyl ketone, 2-quinaldyl ketone, or 2- (o-phenoxy) pyridine ketone, metal bidentate ligand complexes incorporating bisphosphonates, divalent metal maleonitrile dithiolate complexes, molecular charge transfer Complexes, rare earth mixed chelates, (5-hydroxy) quinoxaline metal complexes, aluminum tris-quinolates, and polymers such as poly (p-phenylene vinylene), poly (dialkoxyphenylene vinylene), poly (thiophene), poly (fluorene) , Poly (phenylene), poly (phenylacetylene), poly (aniline), poly (3-alkylthiol N), poly (3-octylthiophene), and poly (N-vinylcarbazole). When a potential difference is applied across the cathode and anode, electrons from the electron injection layer and holes from the hole injection layer are injected into the light emitting layer and recombine to emit light. For OLED and PLED, the following US patent specifications: US Pat. Nos. 5,507,745 (Forrest et al.), 5,721,160 (Forrest et al.), 5,757,026 (Forrest et al.), 5,834,893 (Bulovic et al.), 5,861,219 (Thompson et al.), 5,904,916 (Tang et al.), 5,986,401 (Thompson et al.), 5,998,803 (Forrest et al.), 6,013,538 (Burrows et al.), 6,046,543 ( Bulovic et al.), 6,048,573 (Tang et al.), 6,048,630 (Burrows et al.), 6,066,357 (Tang et al.), 6,125,226 (Forrest et al.), 6,137,223 (Hung et al.), Ibid. Nos. 6,242,115 (Thompson et al.) And 6,274,980 (Burrows et al.).

  In a typical matrix addressed light emitting display device, multiple light emitting devices are formed on a single substrate, and these light emitting devices are arranged in groups in a regular grid pattern. Activation can be done on a row and column basis or in an active matrix with individual cathode and anode paths. OLEDs are often manufactured by first depositing a transparent electrode on a substrate and patterning it to form electrode portions. Next, an organic layer is deposited on the transparent electrode. A metal electrode can be formed on the organic layer. For example, in U.S. Pat.No. 5,703,436 (Forrest et al.), Transparent indium tin oxide (ITO) is used as a hole injection electrode, and an Mg--Ag--ITO electrode layer is used for electron injection. The

The following examples are provided to illustrate the invention.
Example 1
A plain PET overcoated with black or blue contrast layer, Merck BL 118 alone, Merck BL 118 samples were screen printed with EXGHAAMJ-AG conductive UV curable ink from Allied Photochemical. The samples were then cured using a dual lamp fusion UV unit and conveyor system and tested for resistivity.

Sample composition coated with black nano and LC
Prepare aqueous coating dispersion of chiral nematic composition containing 5% gelatin by weight, 8% by weight Merck BL118 obtained from Merck in Darmstadt, Germany, and 0.20% by weight coating surfactant did. Microscopic analysis showed that the dispersion consisted of uniform 8 micron droplets of liquid crystal in an aqueous gelatin medium. A second coating solution was prepared with 4 wt% gelatin and a mixture of nanopigments ground to a size of less than 1 micron was formulated to provide a neutral black concentration. Two layers were applied, and these layers, when combined, resulted in a dry thickness of 14 microns.

Sample composition coated with Blue Nano and LC
Prepare aqueous coating dispersion of chiral nematic composition containing 5% gelatin by weight, 8% by weight Merck BL118 obtained from Merck in Darmstadt, Germany, and 0.20% by weight coating surfactant did. Microscopic analysis showed that the dispersion consisted of uniform 8 micron droplets of liquid crystal in an aqueous gelatin medium. A second coating solution was prepared with 4% by weight gelatin and a mixture of nanopigments ground to a size less than 1 micron was formulated to provide a neutral blue concentration. Two layers were applied, and these layers, when combined, resulted in a dry thickness of 14 microns.

  The composition was applied onto a 5 inch wide polyethylene terephthalate support with ITO sputtered to a resistance of 300 ohms / square, obtained from Bekaert Specialty Films in San Diego, California. Each of the samples was prepared by cutting each sample to a predetermined length and labeled in preparation for screen printing. Immediately prior to the screen printing process, the sample was cleaned using ionized air.

  The samples were then screen printed with Allied Photochemical's EXGHAAMJ-AG conductive silver ink on a DEK 248 screen printer. The image used was a 1 mm matrix design with 15 mm x 15 mm test patches. The screen was made on Sefar America's 7-355-34 polyester mesh.

The curing equipment used was a Fusion FS-300s Dual and FS-300 Single UV lamp, and an LC-6 conveyor system. The dual lamp system was configured so that the sample was exposed using a D bulb followed by an H + bulb. "Single" was a single H valve alone. The energy of each lamp was measured and set to approximately 45 mJ / cm ² in the UVB region using an EIT “power puck” measuring device. The sample was placed on the conveyor after a lamp on time of approximately 5 seconds. FIG. 8 shows the arrangement relationship of the curing devices.

  Once the sample was printed and cured, the sample was then tested for resistivity using a Fluke 83 III multimeter by placing a probe at each corner of a 15 mm x 15 mm test patch. The resistivity test was then performed at the beginning (just cured) at 5, 10, and 30 minute intervals. In addition to the resistivity test, the sample was tested for blocking by placing the sample on a smooth table surface, covering it with a plain PET substrate, and placing a 50 pound weight on top. After 24 hours under the weight, the sample was then examined to look for ink removal or damage. All data was recorded.

  Table 1 reveals that the samples printed and cured with the dual valve system exhibited lower and more stable resistivity in a shorter time. This indicates a more complete cure. Samples with contrast layers that were difficult to cure showed dramatic improvements over those cured with single valve energy. Applying the dual valve spectrum (D and H +) to the various coating layers on the substrate results in very low sheet resistivity, indicating a fully cured polythiophene silver ink. The data in Table 1 is plotted in FIG.

Example 2
Sample composition coated with black nano and LC
Prepare aqueous coating dispersion of chiral nematic composition containing 5% gelatin by weight, 8% by weight Merck BL118 obtained from Merck in Darmstadt, Germany, and 0.20% by weight coating surfactant did. Microscopic analysis showed that the dispersion consisted of uniform 8 micron droplets of liquid crystal in an aqueous gelatin medium. This solution was mixed with 3% by weight of the gelatin cross-linking agent bisvinylsulfonylmethane based on the total amount of gelatin immediately before coating.

  A second coating solution was prepared with 4 wt% gelatin and a mixture of nanopigments ground to a size of less than 1 micron was formulated to provide a neutral black density (CMYK) layer. Two layers were applied, and these layers, when combined, resulted in a dry thickness of 14 microns.

Sample composition coated with carbon black nano and LC
Prepare aqueous coating dispersion of chiral nematic composition containing 5% gelatin by weight, 8% by weight Merck BL118 obtained from Merck in Darmstadt, Germany, and 0.20% by weight coating surfactant did. Microscopic analysis showed that the dispersion consisted of uniform 8 micron droplets of liquid crystal in an aqueous gelatin medium. This solution was mixed with 3% by weight of the gelatin cross-linking agent bisvinylsulfonylmethane based on the total amount of gelatin immediately before coating.

  A second coating solution was prepared with 4 wt% gelatin and a mixture of carbon blacks was formulated to provide a black density (CB) layer. Two layers were applied, and these layers, when combined, resulted in a dry thickness of 14 microns.

Sample composition coated with Blue Nano and LC
Prepare aqueous coating dispersion of chiral nematic composition containing 5% gelatin by weight, 8% by weight Merck BL118 obtained from Merck in Darmstadt, Germany, and 0.20% by weight coating surfactant did. Microscopic analysis showed that the dispersion consisted of uniform 8 micron droplets of liquid crystal in an aqueous gelatin medium. This solution was mixed with 3% by weight of the gelatin cross-linking agent bisvinylsulfonylmethane based on the total amount of gelatin immediately before coating.

  A second coating solution was prepared with 4 wt% gelatin and a mixture of nanopigments ground to a size of less than 1 micron was formulated to provide a blue density (CM) layer. Two layers were applied, and these layers, when combined, resulted in a dry thickness of 14 microns.

  The composition was applied onto a 5 inch wide polyethylene terephthalate support with ITO sputtered to a resistance of 300 ohms / square, obtained from Bekaert Specialty Films in San Diego, California. Each of the samples was prepared by cutting each sample to a predetermined length and labeled in preparation for screen printing. Immediately prior to the screen printing process, the sample was cleaned using ionized air.

  The samples were then screen printed with Allied Photochemical's EXGHAAMJ-AG conductive silver ink on a DEK 248 screen printer. The image used was a 1 mm matrix design with 15 mm x 15 mm test patches. The screen was made on Sefar America's 7-355-34 polyester mesh.

Curing Fusion Unit Configuration The curing equipment used was the Fusion FS-300 Dual and FS-300 Single UV lamps and the LC-6 conveyor system. The dual lamp system was configured so that the sample was exposed using a D bulb followed by an H + bulb. "Single" was a single H valve alone. The energy of each lamp was measured and set to approximately 45 mJ / cm ² in the UVB region using an EIT “power puck” measuring device. After approximately 5 seconds of lamp on time, the sample was placed on the conveyor. Filters (quartz and IR) were housed in an aluminum holder placed between the UV light source and the support. In order to verify the measured values with and without the filter, we adopted UV power pack measured values.

  Once the sample was printed and cured, the sample was then tested for resistivity using a Fluke 83 III multitester by placing a probe at each corner of a 15 mm × 15 mm test patch. A resistivity test was then performed at the start (just cured) and at 30 minute intervals.

  Figure 2 shows that samples printed and cured with only the dual valve system and samples cured with quartz and IR filters are lower in a shorter time than those cured with the single valve system. And show that it showed more stable resistivity. This indicates a more complete cure.

Example 3
The sample utilized in Example 2 above was further evaluated for heat sensitivity. Once the sample was printed and cured, the thermal transition of the coating was evaluated to measure the effect of quartz and IR filters on the elimination / reduction of thermal transition (without affecting the resistivity). In order to identify the presence of thermally transferred liquid crystals, the thermal transition was evaluated by visually observing each sample.

  Table 3 shows that the IR and quartz filters had an effect on the liquid crystal thermal transition. Thermal transitions were rated on a scale of 1 to 3 (1 = thermal transition, 2 partial, and 3 absent). Table 3 shows that the BL118 alone sample performed well and all the rest was thermally transferred. The color of the contrast layer or pigment layer can, in some cases, cause the heat transfer (IR absorption of the liquid crystal layer to be higher than when using a filter) as a result of higher heat generated during the UV curing process due to the opacity of the pigment dark layer coating. Have a great impact on The coating containing the pigment layer or dark layer on the liquid crystal layer was thermally transferred during the UV curing process when a heat reduction mechanism, such as a heat sink, was not used under the panel.

Example 4

  Table 4 shows the Michigan when screen printed using 325 stainless steel mesh and exposed at comparable UVB exposure levels in both the Fusion FS-300 Dual wavelength unit and the new coalesced beam dual wavelength unit. The conductivity of EXGHAAMJ-AG (389) UVB curable conductive silver ink from Allied Photochemical in Kimball State is shown. The FS-300 dual unit was subjected to H + bulb exposure following D bulb exposure. The exposure delay between the bulbs was 1.4 seconds on the FS-300 unit. The combined beam dual wavelength unit of the present invention is configured to have both D and H + as shown in FIG. 6, and both beams are combined to expose the substrate simultaneously. The substrate used in Table 4 is a cholesteric liquid crystal, and a dark layer is provided on the ITO and PET substrates as described above.

  These results quantitatively show a significant improvement in cure over the prior art as measured by a dramatically improved conductivity 2 minutes after exposure. Is Allied EXGHAAMJ-AG (389) silver-containing PTF ink exposed to infinite resistance when exposed in a FS-300 unit dual wavelength unit with a 1.4 second delay between exposure by the D and H + bulbs? Or no electrical conductivity. Simultaneous exposure of the same ink during the same exposure with the same D bulb and H + bulb combined in the assembly of the present invention results in a low resistance of 3.1, 2.9, and 8.9 ohm / square for the three samples. Reduced resistance is a direct measure of cure rate. As is apparent from the 24-hour data, the ink exposed by the FS-300 dual system eventually becomes conductive, but does not have the conductivity as much as the simultaneous exposure of the present invention. If rapid curing without long holdings is desired, for example in the case of winding in a roll-to-roll process, a dramatically improved curing rate is very advantageous. Reduced resistance or higher conductivity is a very advantageous property for many circuit applications.

  While the invention has been described in detail with particular reference to certain preferred embodiments, it will be understood that changes and modifications can be made within the spirit and scope of the invention.

FIG. 1 illustrates the use of a mirror, an infrared absorbing mirror, and one or more stacked IR or light absorbing filters in the optical path to contact a curable material on a substrate or support. FIG. 2 shows a system for combining two optical paths into a single path. Figure 2 shows how to combine two optical paths into a single path by utilizing mirrors, refractive elements, infrared absorbing mirrors, and one or more stacked IR or light absorbing filters in the optical path. It is a figure which shows a system. FIG. 3 shows that two or more stacked IR or light absorbing filters are used and two lamp assemblies are positioned / angled so that the combined lamp spectrum reaches the substrate. It is a figure which shows the system for uniting an optical path to a single path. FIG. 4 shows that the lamp assembly is arranged horizontally and the two light paths are directed to the infrared absorbing mirror and pass through one or more stacked IR or light absorbing filters. FIG. 2 shows a system for combining two optical paths into a single path. FIG. 5 shows a prior art Fusion UV conveyor assembly and dual lamp irradiator system. This figure shows the main system components and the air flow through the system. FIG. 6 is a diagram showing a preferred embodiment of the present invention. FIG. 7 is a plot of the substrate resistivity results of Example 1, Table 1 (for the single lamp, the prior art Fusion dual lamp of FIG. 5 with the light source separated, and single or dual UV exposure at 13 ft / min. Transported through the unit). FIG. 8 is a diagram showing the configuration of the curing device used in the example.

Explanation of symbols

1 Lamp supply cooling air inlet
2 UV lamp assembly
3 Lamp assembly and belt transport chamber
5 Vacuum supply / lamp exhaust port
6 Upper chamber lamp exhaust port
7 Upper / lower chamber isolation assembly
8 Upper chamber
9 Lower chamber
10 First lamp reflector
11 First lamp
12 folding mirror
13 Combined mirror
14 Optical filter
15 Board
16 Second lamp
17 Second lamp reflector
20 Refraction element
30 Upper chamber
31 Lower chamber
32 Lower chamber exhaust / vacuum supply
33 Upper chamber exhaust port
34 Perforated transport belt
35 Infrared reflector / absorber
36 Frame for optical filter
37 Heat exchanger plate with holes
38 Second lamp funnel mirror
39 First lamp funnel mirror
40 Mechanical shut-off

Claims (39)

  A cured assembly comprising at least two light sources, each of the at least two light sources having a spectrum, each of the spectra of the at least two light sources being combined in one optical path, and the at least two A curing assembly in which two light sources can cure the material exposed to the one combined optical path.   The cured assembly of claim 1, wherein the at least two light sources have different spectra.   The cured assembly of claim 1, wherein the at least two light sources are at least one short wavelength UV bulb and at least one long wavelength UV bulb.   The cured assembly of claim 1, further comprising at least one reflector for combining the spectra of each of the at least two light sources into one optical path.   2. The cured assembly of claim 1, wherein the reflector is a mirror.   6. The cured assembly of claim 5, wherein the mirror is a cold mirror, and the cold mirror reflects a portion of the spectrum of each of the at least two light sources.   6. The cured assembly of claim 5, wherein the mirror is a hot mirror, and the hot mirror absorbs a portion of the spectrum of each of the at least two light sources.   The cured assembly of claim 1, further comprising at least one refractive element for combining the spectra of each of the at least two light sources into one optical path.   The cured assembly of claim 1 further comprising a filter.   10. The cured assembly according to claim 9, wherein the filter is a visible light filter.   10. The cured assembly according to claim 9, wherein the filter is an IR filter.   The cured assembly of claim 1, wherein the at least two light sources have adjustable intensity.   The cured assembly of claim 12, wherein the adjustable intensity is adjusted by changing a focal length, the focal length being a distance from the material to the at least one light source.   The cured assembly of claim 1, further comprising a shutter between the material and the at least one light source.   The cured assembly of claim 1 further comprising a heat reduction system.   The curing assembly of claim 1, wherein the material is a photocurable material associated with a heat sensitive material, and the photocurable material is disposed between the one combined optical path and the heat sensitive material. body.   The cured assembly of claim 16, wherein the material is an electrically imageable material.   18. A cured assembly according to claim 17, wherein the electrically imageable material is a polymer dispersed liquid crystal (PDLC) material.   The cured assembly of claim 15 further comprising a color contrast pigment layer.   2. The cured assembly of claim 1, wherein the material is a heat sensitive material.   The cured assembly of claim 1, further comprising at least one reflector, at least one shutter, and a heat reduction system.   The cured assembly of claim 21, further comprising at least one filter.   The cured assembly of claim 21, wherein the heat reduction system comprises at least one heat sink, at least one heat exchanger, or a combination thereof.   The cured assembly of claim 21, wherein the at least one reflector includes a hot mirror and a funneled mirror.   The cured assembly of claim 21, wherein the curable material is associated with a liquid crystal layer and at least one color contrast pigment layer. Providing a curable material; and exposing the curable material to a coalescing light path from the cured assembly, the cured assembly including at least two light sources, each of the at least two light sources having a spectrum. The spectrum of each of the at least two light sources is merged into one optical path, and the at least two light sources are capable of curing the material exposed to the one merged optical path;
A method of curing the material.   27. The method of claim 26, wherein the method is a roll-to-roll process or a continuous process.   27. The method of claim 26, wherein the material is a photocurable material associated with a heat sensitive material, and the photocurable material is disposed between the one combined optical path and the heat sensitive material. .   29. The method of claim 28, wherein the curable material is associated with a liquid crystal layer and at least one color contrast pigment layer.   27. The method of claim 26, wherein the at least two light sources have different spectra.   27. The method of claim 26, wherein the at least two light sources are at least one short wavelength UV bulb and at least one long wavelength UV bulb.   27. The method of claim 26, wherein providing the curable material is providing a curable material on a moving belt.   27. The method of claim 26, further comprising removing heat using a heat reduction system.   34. The method of claim 33, wherein the heat reduction system comprises at least one heat sink, at least one heat exchanger, or a combination thereof.   27. The method of claim 26, further comprising opening a shutter between the material and the at least one light source prior to the exposure and closing the shutter after the exposure.   27. The method of claim 26, further comprising at least one reflector for combining the spectra of each of the at least two light sources into one optical path.   27. The method of claim 26, further comprising at least one refractive element for combining the spectra of each of the at least two light sources into one optical path.   27. The method of claim 26, further comprising a filter.   27. The method of claim 26, wherein the material is a heat sensitive material.

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